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PubMed1997

Curvilinear relationship between blood lead level and reaction time. Differential association with blood lead fractions derived from exogenous and endogenous sources.

Prior studies demonstrate an inconsistent relationship between occupational inorganic lead exposure and simple reaction time (SRT) performance. In this study, we administered a computerized SRT test to 78 currently employed lead smelter workers and then investigated the relationship between different measures of blood lead and components of SRT performance. The measures of blood lead included current blood lead (PbB) and mathematically derived blood lead fractions from the environment (PbB-env) and from bone (PbB-bn). Measures of SRT performance, obtained from 44 trials with interstimulus intervals (ISIs) ranging from 1 to 10 seconds, included median SRT (SRT-md), mean SRT for ISIs between 1 and 5 seconds (SRT-1-5), and mean SRT for ISIs between 6 and 10 seconds (SRT-6-10). Multiple regression analysis after adjustment for age and education revealed a curvilinear relationship between PbB and SRT-md. As PbB increased from 0 to 30 micrograms dl-1, SRT-md decreased, and only with PbB levels above 30 micrograms dl-1 did SRT-md increase. PbB terms accounted for 13.7% of the variance in this SRT measure (P < 0.01). The longer ISI variable, SRT-6-10, was found to be more strongly related to PbB, to have lesser variability across ISIs, and to be unrelated to age. Additional multiple regression analysis to examine the relationship between components of SRT and the PbB fractions, PbB-env and PbB-bn, showed only PbB-env to account for significant variance in SRT-md, (14.4%, P < 0.01), SRT-1-5 (9.7%, P < 0.03), and SRT-1-6 (15%, P < 0.01). We conclude that the relationship between PbB and SRT is U-shaped, that the SRT measure SRT-6-10 has properties that make it the preferred measure of SRT performance in future studies, and finally that only PbB-env, and not PbB-bn, is related to components of SRT.

Adult↗
PubMed1985

Total contribution of airborne lead to blood lead.

A nine year study of blood lead concentrations and isotope ratios carried out on a married couple shows that pulmonary deposition cannot account for all the airborne lead in blood; that lead from bone may comprise 70% of blood lead; and that during pregnancy blood lead may double due to mobilisation of lead from bone.

Adult↗
PubMed1991

The use of K X-ray fluorescence for measuring lead burden in epidemiological studies: high and low lead burdens and measurement uncertainty.

X-ray fluorescence (XRF), a rapid, noninvasive, low-radiation-dose method of measuring bone lead content, has emerged as a promising tool for providing an integrated estimate of low-level lead accumulation in epidemiological studies. Our group has settled on an XRF instrument that utilizes K X-rays (K-XRF) and normalizes the measurement to bone calcium. The unit of measurement provided is in micrograms of lead/gram bone mineral, an accurate proxy for micrograms of lead/gram bone ash. An estimate of measurement uncertainty is generated from the counting statistics and is theoretically dependent on several factors, primarily duration of measurement and bone mass. Data from pilot studies of community-exposed adults and workers with varying degrees of occupational lead exposure demonstrated that the K-XRF instrument can easily distinguish between populations with occupational versus environmental lead exposures. Among all subjects, bone lead increased with age. Larger measurement uncertainty was significantly associated with being female, greater subject weight, and smaller lead burdens.

Adult↗
PubMed1992

Lead exposure in the construction industry: results from the California Occupational Lead Registry, 1987 through 1989.

The construction industry is exempt from the medical monitoring portions of the US Federal Occupational Safety and Health Administration General Industry Lead Standard. Of 28 construction workers reported to the California Occupational Lead Registry through March 1989, 11 (39%) had blood lead levels of 2.90 mumol/L (60 micrograms/dL) or greater, the level at which immediate removal from lead exposure is mandated in nonconstruction industries. Many workers had not been warned of possible lead exposure. The exemption of the construction industry from the General Industry Lead Standard should be reconsidered.

California↗
PubMed1994

Elevated blood lead levels among construction workers in the Massachusetts Occupational Lead Registry.

Although the construction industry until recently was exempt from the Occupational Health and Safety Administration General Industry Lead Standard, including its medical monitoring provisions, periodic blood lead tests have been required for residential "deleaders" and structural painters in Massachusetts. Sixty-three percent of the 381 registrants in the Massachusetts Occupational Lead Registry with blood lead levels of 1.93 mumol/L or higher are construction workers. This proportion is much higher than that reported by registries of several states selected for comparison. These data highlight the need for better protection from lead exposure and the effectiveness of mandatory medical surveillance in identifying elevated blood lead levels among construction workers.

Adolescent↗
PubMed1998

Excretion of triethyllead, diethyllead and inorganic lead in rabbits after injection of triethyl neopentoxy lead.

Triethyl neopentoxy lead (TEneoPOL: (C2H5)3Pb [OCH2C(CH3)3] liquid) was administered to rabbits in a single dose of 10 mg/kg body weight (5.4 mg Pb/kg body weight), and the urinary and fecal excretions of lead were measured to determine the fate of this triethyllead derivative. About 4% of the administered amount of was excreted into the urine during the 7 days after the injection; and about 68%, into the feces. In other words, the fecal excretion of total lead was about 17 times as great as the urinary excretion. About 85% of the urinary excretion of total lead was composed of diethyllead (Et2Pb2+), and about 92% of the fecal excretion consisted of inorganic lead (Pb2+). The major chemical species of lead excreted in the urine was Et2Pb2+, while the major species excreted in the feces was Pb2+. These results were similar to those of administration of tetraethyllead (Et4Pb) to rabbits. One of the 7 rabbits died on the day following the injection, and TEneoPOL, a triethyllead derivative, proved to be no less toxic than Et4Pb. However, this compound is immediately hydrolyzed by the ambient moisture to form a white solid compound, so that it is not accompanied by as great a risk of airway exposure as Et4Pb.

Animals↗
PubMed2004

Relationship between increased blood lead and pregnancy hypertension in women without occupational lead exposure in Tehran, Iran.

This study was conducted to assess the relationship between blood lead levels and pregnancy-induced hypertension. Participants were 110 pregnant women, of whom 55 were hypertensive, 27 +/- 5.6 yr of age (mean +/- standard deviation) (range = 17-40 yr); the other 55 women were age- and gravidity-matched normotensive controls. Participants were selected on the basis of their medical history and the results of a questionnaire-based interview. Subjects were at gestational ages 37 +/- 2.5 wk (range = 30-41 wk) and were not occupationally exposed to lead. Blood samples were collected within 24 hr after delivery, and blood lead levels were measured. For the hypertensive cases, blood lead levels were 5.7 +/- 2 microg/dl (range = 2.2-12.6 microg/dl [0.27 +/- 0.10 micromol/l; range = 0.11-0.60 micromol/l]), which were significantly higher than those of the control group (i.e., 4.8 +/- 1.9 microg/dl; range = 1.9-10.6 microg/dl [0.23 +/- 0.09 micromol/l; range = 0.09-0.51 micromol/l]). There were no significant differences in blood lead concentrations among hypertensive subjects with proteinuria (n = 30) and those without proteinuria (n = 25). Results of this study indicated that low-level lead exposure may be a risk factor for pregnancy hypertension.

Adolescent↗
PubMed1987

Lead exposure during demolition of a steel structure coated with lead-based paints. I. Environmental and biological monitoring.

Demolition of a steel railway bridge was carried out by nine workers using flame-torch cutting. The air in the breathing zone of the workers contained from 2 to 38 mg of lead/m3, which is a very high level in comparison with the Dutch exposure limit of 0.15 mg/m3 (8-h time-weighted average). Without very effective respiratory protection these concentrations may result in acute lead poisoning. Upwind of the flame-torch exposure the level was below the exposure limit, whereas downwind lead concentrations of up to ten times the exposure limit were observed. Although filtering facepieces were used by the workers, average blood lead concentrations of about 4.5 mumol/l were rapidly attained. Possibly under these work conditions this value represents a maximum concentration attainable in blood. After termination of the exposure, there was a fast decrease of lead in the blood. This finding indicates that lead was mainly present in rapidly exchangeable compartments like blood. No stable correlation between the concentration of lead in blood and the concentration of zinc protoporphyrin in blood was found.

Air Pollutants, Occupational↗
PubMed1998

Lead concentrations in tibial and calcaneal bone in relation to the history of occupational lead exposure.

OBJECTIVES: This study tested a simple model of the relationship between the lead concentration in bone (bone-Pb), exposure time, and lead in plasma (P-Pb) and whole blood (B-Pb) to make it possible to use bone-Pb as a retrospective exposure index. METHODS: Seventy-seven active lead workers and 24 referents were studied. The bone-Pb in tibia (T-Pb) and calcaneus (C-Pb) was measured by in vivo X-ray fluorescence. P-Pb was calculated from B-Pb by use of the nonlinear relationship between these variables. Cumulative B-Pb (cumB-Pb) and P-Pb (cumP-Pb) were calculated to the time of the bone-Pb measurements. In addition, cumP-Pb was adjusted by applying varying rate constants for the transfer of lead from bone to plasma. RESULTS: There were close linear associations between the lead concentrations in tibia (proportion of variance explained, R2 = 0.78) and calcaneus (R2 = 0.80), on one hand and the cumB-Pb on the other. The best fit of bone-Pb to the adjusted cumP-Pb (0.79 for T-Pb; 0.82 for C-Pb) was obtained for the terminal phase half-times of 13 and 12 years, respectively. CONCLUSIONS: The combined data on bone-Pb and exposure time make it possible to estimate previous mean P-Pb and B-Pb. Such estimates will be valuable in studies of toxic effects on long-term exposed lead workers when data on the intensity of previous exposure are lacking. The use of P-Pb in modeling bone-Pb kinetics is physiologically relevant, but the use of adjusted cumP-Pb, as compared with cumB-Pb, did not significantly change the variance in the relation to bone-Pb.

Adolescent↗
PubMed2000

[Relationship between blood lead and free erythrocyte-protoporphyrin of female workers exposed to low concentration of lead operating environment].

The thesis focused in the research on whether low-lead operation would have effects on female workers. Based on investigation of 82 female workers under an operation environment with lead concentration of 0.0315 mg/m3, the following report indicated that differences did exist in terms of free erythrocyte-protoporphyrin(FEP), lead-blood(Pb-B) and lead-urine(Pb-U) values between the exposure and control groups. Pb-B, FEP and Pb-U were found closely interrelated and comparatively sensitive. Dose-response relationship was discovered in the process, positive percentage of Pb-B and FEP were 20.73% and 21.95% respectively, 13.4% above the maximal standard in both cases. In consequence, it was concluded that exposure to the 0.0315 mg/m3 lead concentration (0.03 mg/m3 being the normal) was still harmful to the female workers. Apart from that, the article suggested that the upper limit of lead in blood for common women (in Changchun city) was properly defined at 1.46 mumol/L. With FEP as the standard, the article made repective comparisons on the female workers' intelligence quotient (IQ) and the symptom occurrence of the neural system. People with IQ value between 60 to 79, 80 to 89, 90 to 109 or 110 to 119, the rates of showing positive report with FEP > or = 0.90 mumol/L were 27.6%, 22.6% and 15.0% respectively. The general occurrence rate on various level of FEP was obviously higher than that of the control group. The highest occurrence rate of 208.32% and 58.74% appeared when the FEP value was between 0.36 mumol/L to 0.54 mumol/L. When we made the comparison according to different symptoms as headache, dizziness, hypomnesis, somnipathy, palpitation and ephidrosis, the occurrence rate of headache was distinctively highger than that of the somnipathy.

Adult↗
PubMed2003

These studies were conducted to assess the effects of lead toxicity on exploratory behavior and running. Effects of lead on exploratory behavior and running speed in the shrew, Blarina brevicauda (Insectivora).

These studies were conducted to assess the effects of lead toxicity on exploratory behavior and running speed in the short-tailed shrew, Blarina brevicauda. Shrews from the experimental group received 25 mg/kg/day of lead acetate in their drinking water for a period of 90 days. Control subjects received sodium acetate. Exploratory behavior was determined using a computerized activity chamber where movements of test subjects broke infrared beams projected onto the floor of the apparatus. Time spent (sec) in exploration was recorded over eight 6-min intervals. Running speed (km/hr) was measured in a microprocessor-controlled rectangular racetrack fitted with photocell timers. With respect to time spent in exploration, there were significant differences between lead-exposed (20.5-23.9 sec per 6-min testing session) and control subjects (6.8-8.1 sec) after the sixth testing interval in the activity chamber. With respect to maximal running speed, control subjects ran significantly faster (mean: 14.8 km/hr) than their lead-exposed counterparts (5.83 km/hr). Lead-exposed animals exhibited hyperactivity and increased random locomotor movements. They would frequently bump into the walls and their movements were more random. Controls typically ran along the racetrack in a straight line. These results represent the first data for the effects of lead exposure on exploratory behavior and running speed for shrews.

Animals↗
PubMed1989

[Prenatal lead blood levels in a city heavily exposed to lead].

The blood lead concentrations were measured in 38 pregnant women and their newborn babies in a high exposure area. The lead content of human milk was also determined on the 5th day after delivery. The blood lead concentrations were higher than 12 micrograms/100 ml in more than 80 per cent of the samples. The lead content of breast milk was also greater than those of published recently. We found a strong correlation between the blood lead levels of the mothers and the newborns. There was a moderate correlation between the lead concentrations in the blood and the breast milk.

Air Pollutants↗
PubMed1988

Prenatal lead exposure and its potential significance for developmental disabilities: a preliminary study of umbilical cord blood lead levels.

It has been reported that between 1976-1980 the mean blood lead level in American preschool children was 16 micrograms/dl. The Centers for Disease Control (CDC) recently set a blood level of 25 micrograms/dl as the highest acceptable level for children. However, current research findings have provided evidence that detrimental effects on development can occur when lead levels are below this acceptable value. In particular, recent work has shown a relationship between early (prenatal) exposure to lead and delayed cognitive development. Because the developing fetus is particularly vulnerable to insult, it is of critical importance to obtain information about the developmental effects of prenatal exposure to lead and about those factors that may influence this exposure. This report presents initial findings of an ongoing investigation pertaining to issues surrounding early lead exposure. To date umbilical cord blood samples have been measured in 802 infants born at Children's Hospital of Buffalo between November 1987 and April 1988. These infants' residence span approximately 50 townships with most residing in Buffalo proper. Approximately 60 percent of the infants had measurable cord blood lead levels in the range of 4 to 20 micrograms/dl.

Cognition Disorders↗
PubMed1982

Electrophysiological study of subjects occupationally exposed to lead and with low levels of lead poisoning.

The relationship between the length of exposure to lead, blood lead level (PbB), and peripheral nerve damage in a population occupationally exposed to low lead levels was evaluated. Sixty-two foundry workers were studied whose length of exposure ranged from 5 months to 10 a; their mean PbB in the last 2 a had not exceeded 50 microgram/100 ml (2.4 mumol/l). The referents were 27 hospital employees, of comparable ages, not occupationally exposed to lead. The electrophysiological examination consisted of the determination of the motor conduction velocity (MCV) of the median, and peroneal nerves, sensory conduction velocity (SCV) of the median and sural nerves, and the latency of the T and H reflexes. The mean MCV, SCV and the amplitude of the sensory action potential (SAP) of the median nerve were significantly lower in the group of exposed workers than in the reference group. When the exposed subjects were divided into three groups according to length of exposure, no difference was observed between the three groups. When they were divided into different groups according to the maximum PbB (max PbB) value, the observed differences with respect to the reference groups were already present in those with a max PbB of less than 50 microgram/100 ml (less than 2.4 mumol/l), but were more evident in the subjects with a max PbB of greater than 70 microgram/100 ml (greater than 3.4 mumol/l). Within the group of subjects with a max PbB of 50-69 microgram/100 ml (2.4-3.3 mumol/l), the differences with respect to the reference values were more evident for subjects with a short length of exposure (less than 2 a). The MCV of the median nerve correlated with the time since the PbB exceeded 50 microgram/100 ml (2.4 mumol/l). In conclusion, the electrophysiological changes observed in lead-exposed subjects do not seem correlated with the length of exposure. Such alterations seem more evident in those subjects whose PbB has been greater than 70 microgram/100 ml (3.4 mumol/l) at least once during the preceding 2 a and in those subjects who, at the time of the neurophysiological examination, have a PbB greater than 50 microgram/100 ml (2.4 mumol/l). The apparently greater sensitivity to lead in new employees, compared to workers with a longer exposure time, remains to be clarified.

Adult↗
PubMed1998

[Blood lead concentration in the Danish population after introduction of lead-free gasoline].

Blood lead concentrations in a Danish reference population were related to information from an extensive questionnaire on work, environment and life style. The mean concentration of lead in blood was 0.167 mumol/L, i.e. significantly lower than in previous studies. This finding is in accordance with the fact that less than 10% of petrol used in Denmark contained lead additives (up to 0.15 g/L). An important finding was that the well-documented predictors for lead in blood at higher concentration levels, such as age, gender, menopausal status, and intake of alcohol, are still valid in a low-level exposure situation. In addition, a strong and negative correlation was found between blood lead concentrations and dietary supplementation with vitamins and minerals. The present data indicate that lead exposure may still constitute a health risk in a small proportion of adult males and postmenopausal women.

Adult↗
PubMed1976

A 46,XY, del(18)(pter leads to p1 100:) cebocephalic child from a 46,XX,t(12;18)(18pter leads to 18 p 1100:: 12qter leads to 12pter) normal parent.

A normal female with an 18p--chromosome but without any feature of the 18p--syndrome produced a cebocephalic child whose karyotype included an 18p--chromosome. Evidence is presented that the normal female is a nonreciprocal translocation heterozygote resulting from the short arm of one chromosome 18 becoming attached to the long arm of a chromosome 12.

Abnormalities, Multiple↗